Not likely to happen or be true.

Feeling uncertain about something.

संदिग्ध

English Usage: His explanation seemed improbable; I found it very doubtful.

Hindi Usage: उसकी व्याख्या संदिग्ध लग रही थी; मुझे यह बहुत ही संदिग्ध लगा।

The quality of being improbable; unlikelihood.

असंभवता

English Usage: The improbability of the situation made it more intriguing.

Hindi Usage: परिस्थिति की असंभवता ने इसे और भी दिलचस्प बना दिया।